Universität Potsdam, Institut für Biochemie und Biologie, Molekularbiologie, Heisenberg-Gruppe Biophysik und Molekulare Pflanzenbiologie BPMPB, Karl-Liebknecht-Strasse 24-25, Haus 20, Potsdam-Golm, Germany.
Mol Plant. 2010 Jan;3(1):236-45. doi: 10.1093/mp/ssp096. Epub 2009 Dec 10.
The family of voltage-gated (Shaker-like) potassium channels in plants includes both inward-rectifying (K(in)) channels that allow plant cells to accumulate K(+) and outward-rectifying (K(out)) channels that mediate K(+) efflux. Despite their close structural similarities, K(in) and K(out) channels differ in their gating sensitivity towards voltage and the extracellular K(+) concentration. We have carried out a systematic program of domain swapping between the K(out) channel SKOR and the K(in) channel KAT1 to examine the impacts on gating of the pore regions, the S4, S5, and the S6 helices. We found that, in particular, the N-terminal part of the S5 played a critical role in KAT1 and SKOR gating. Our findings were supported by molecular dynamics of KAT1 and SKOR homology models. In silico analysis revealed that during channel opening and closing, displacement of certain residues, especially in the S5 and S6 segments, is more pronounced in KAT1 than in SKOR. From our analysis of the S4-S6 region, we conclude that gating (and K(+)-sensing in SKOR) depend on a number of structural elements that are dispersed over this approximately 145-residue sequence and that these place additional constraints on configurational rearrangement of the channels during gating.
植物电压门控（Shaker 样）钾通道家族包括内向整流（K(in)）通道，其允许植物细胞积累 K(+)，以及外向整流（K(out)）通道，其介导 K(+)外排。尽管它们具有密切的结构相似性，但 K(in)和 K(out)通道在其对电压和细胞外 K(+)浓度的门控敏感性方面存在差异。我们已经在 K(out)通道 SKOR 和 K(in)通道 KAT1 之间进行了系统的结构域交换计划，以检查对门控的孔隙区域、S4、S5 和 S6 螺旋的影响。我们发现，特别是 S5 的 N 端部分在 KAT1 和 SKOR 门控中起着关键作用。我们的发现得到了 KAT1 和 SKOR 同源模型的分子动力学的支持。计算机分析表明，在通道开放和关闭过程中，某些残基的位移，特别是在 S5 和 S6 片段中，在 KAT1 中比在 SKOR 中更为明显。从我们对 S4-S6 区域的分析中，我们得出结论，门控（和 SKOR 中的 K(+)-感应）取决于许多结构元素，这些元素分散在大约 145 个残基序列中，并且这些元素在门控过程中对通道的构象重排施加了额外的限制。
